An individual reception of TV and radio programmes from geostationary satellites has extended throughout the world. Both national public service broadcasters and commercial companies offer their programmes through satellite stations. Also data services, such as a high speed connection to internet, are provided by means of satellites. A typical satellite signal receiving system consists of several basic components. Such a system comprises an aerial, an external unit, a coaxial cable and a satellite signal receiver. The external unit, located in an aerial focus, amplifies a signal and changes its frequency, the satellite signal receiver after processing the signal transfers it into a sound and/or image output. The external unit, the converter is commonly depicted as LNB element.
While many users of the system are satisfied with reception from only one orbit station, there exist an increasing number of those who request reception from two or even more satellite stations. Programmes designated for a specific group of people are very often broadcast through several satellites, like Czech spoken programmes, which are currently broadcast partly through the Astra satellite system positioned at an orbital position 19.2 degrees east, partly through a Eurobird satellite positioned at 28.5 degree east. And last but not least there exists also a large group of people interested in foreign language spoken programs. Moreover there is known a large community of so called signal hunters, known also as DX-ers.
A satellite signal reception is characterised by application of parabolic type aerials manifesting large signal gain and narrow emissive characteristic. The narrow reception signal beam prevents mutual disturbance of signals from different satellites, on the other hand a standard reception system provides for a reception of a signal from only a single satellite. The problem of a reception from several satellite positions has so far found two principal solutions. There is used either a motor-controlled reception aerial or two or more reception sets each of them having a fixed aerial. The motor-controlled reception aerial manifest a versatility as it can be oriented towards any visible position on a satellite orbit. On the other hand there is a time lag between positions and such an aerial cannot be shared by several participants. The system of fixed aerials having with converters connected to a satellite receiver through a change-over switching device offers an advantage of an immediate reception from a selected satellite and the system can be used simultaneously by more participants. The system is not so complicated and its related costs not so high as it may seem to be as a reflecting surface of one aerial can be used for several external units. On a common, so called offset parabolic aerial there may be placed up to four external units and there exist special aerials having a toroidal shaped reflecting surface where it is possible to arrange eight or even more external units. With respect to constantly decreasing costs of external units, a price of such a so called multi focus reception system comes close to that one of systems with a motor controlled aerial.
A satellite receiver provides not only for a decoding of a radio signal but also for a control of other parts of a respective receiving system, primarily for a control of an operational mode of an external unit, i.e. for a selection of incoming signal according to a polarisation and a frequency range. In a case of a reception from several satellite positions, irrespective to an applied system with a motor controlled aerial or switching of several converters, there exists a need to control a selection of a desired satellite position. In a current praxis there is more and more promoted a communication protocol commonly known as a “DiSEqC standard” created by a French company Eutelsat. This protocol integrating all desired control function into one complex digital command system has practically become an international standard. The command together with high-frequency signals are transferred by a co-axial cable interconnecting all parts of a receiving unit.
Apart from a control of the external unit operation mode, the basic version of the DiSEqC 1.0 standard enables also change-over switching between four satellite positions. Such a solution is widely used and DiSEqC relays are commonly manufactured.
If a user requests switching between five and more converters, he can use a DiSEqC 1.1 standard, which allows for a control of more extensive system. This standard e.g. makes possible an arrangement of sixteen converters into four equal groups each group being furnished with a common four-input change-over switch operating under the DiSEqC 1.0 standard. Having mechanical and cable installations completed, necessary addresses of all applied change-over switches are defined in a configuration menu of a receiver for each converter. Thus the system is ready for operation. Despite the fact the DiSEqC 1.1 standard enables to switch over even 64 inputs, it has not become widely used. This is due to rather complicated network and the fact that the DiSEqC 1.1 standard has not been considerably supported by manufacturers of satellite receivers.
For needs of motor controlled aerials there has been developed a DiSEqC 1.2 standard which provides also for commands controlling motor operation and stops, storing of aerial mechanical positions, transfer to a stored position and some other auxiliary functions. The most demanding step by installation of a system operating under the DiSEqC 1.2 standard, apart from an assembly of mechanical parts, is an identification of motor positions for individual satellites. This step is performed by consecutive rotation of the receiving system so long as a respective satellite signal appears on a monitor. The found mechanical position is stored in a rotator memory. In such a way all desired position of an aerial are defined and stored. The configuration being completed a reception of a signal from a required satellite is performed by turning the aerial to the respective stored position.
The DiSEqC 1.2 standard is widely supported and is a part of equipment of satellite receivers. Due to continuous fall of costs of converters there exists an increased interest in static multi focus installations but the obsolete DiSEqC 1.2 standard allows for only four converters to be switched over. Such a situation does not meet current demands of the market.
It is an object of the present invention to increase possibilities of reception of signals from more satellites while using a system with fixed aerials.